1. Field of the Invention
The present invention relates generally to a unicast-based network. More particularly, the present invention relates to relaying data in a unicast-based network.
2. Description of Related Art
A group message service via Internet is typically performed in a manner that a server transmits the same message data to each of the terminals included in the group message. While this method increases load in a server and a network in proportion to the number of terminals involved, its implementation and user management are quite easy. As a result, this method is used in most communication environments.
When such a group message service is provided, a multicast scheme is applied to avoid the repetitive transmission as in the unicast scheme and to efficiently utilize network resources. To use the multicast scheme in a Voice over Internet Protocol (VoIP) system of the related art, all of the routers along the traffic path need to support the multicast protocol and to maintain the transmission tree per session.
However, most of the currently available routers do not support multicast. To apply the multicast scheme, the most adequate method for building the group tree should be selected according to the number, densities, and distribution of transmitters and receivers overall, which may be difficult. Consequently, since it is difficult to apply the multicast transmission to the actual VoIP system environment, an application layer multicast scheme is studied as the alternative.
The application layer multicast scheme relays data between terminals in the application layer, and can reduce the load of the server and prevent the load from concentrating to a particular node or path by distributing the traffic over the network topology. However, since the application layer multicast scheme according to the related art mostly focuses on the multicast effect, it does not offer an efficient method for building the group for the actual group message service.